Abstract

A total of 1248 animals was stunned in two EU approved slaughterhouses using
either cartridge activated or pneumatic concussion stunning devices. In total,
12 % of the animals had to be stunned twice. If the shooting position deviated
from the midline the rate of re-stunning increased considerably. In the main
experiment carried out in the larger of the two slaughterhouses 67.8 % of the
animals lay without any movement immediately after falling out of the stunning
box.
Pathological examinations carried out after splitting the skull longitudinally
showed a low to high degree of haematoma formation in the brain in more than
half of the animals stunned by concussion stunning. The haematomas were
localized on the frontal side of the brain immediately beneath the stunning
position and on the opposite side of the brain stem. The haematomas occurred
also in animals the lamina interna and the dura mater of which were not injured.
Following concussion stunning 69 electrocardiograms were made. Except for one
animal which could not be evaluated all animals showed normal heart activity
corresponding to that observed after captive bolt stunning.
The examination of several meat quality parameters did not yield any clear
deviations from meat maturation after captive bolt stunning. Meat color, pH
value and temperature were measured in the Musculus longissimus dorsi.
The most important conclusion of this study is that the application of
concussion stunning can improve the safety of the slaughterhouse workers in
several critical positions of the slaughtering line (stunning, hoisting and
sticking). As long as the dura mater remains intact, the worker responsible for
stunning does not come into contact with potentially infected brain material. In
addition, after concussion stunning carcass stillness was clearly improved in
comparison to captive bolt stunning.
However, the results concerning animal welfare are still unsatisfactory as too
many animals have to be stunned twice. With respect to consumer protection
concussion stunning also does not offer advantages over captive bolt stunning
since the distribution of nerval tissue via blood cannot be ruled out because of
the haemorrhages occurring in the brain.